By way of example, lithography installations are used in the production of integrated circuits or ICs for imaging a mask pattern in a mask onto a substrate such as e.g. a silicon wafer. In so doing, a light beam generated by an optical system is directed through the mask onto the substrate.
Driven by the desire for ever smaller structures, particularly in the production of integrated circuits, EUV lithography installations that use light with a wavelength in the range from 5 nm to 30 nm, in particular 13.5 nm, are currently under development. “EUV” denotes “extreme ultraviolet”. In the case of such lithography installations, because of the high absorption of light of this wavelength by most materials, reflective optics, that is to say mirrors, have to be used instead of—as previously—refractive optics, that is to say lenses.
The provision of mirrors in the form of so-called mirror fields (also referred to as mirror arrays), which may include several hundred thousand mirrors, is known. Here, the mirrors are each tiltable about one axis or two mutually perpendicularly oriented axes in order to guide the light on a suitable path to the substrate to be exposed. The light incident on a respective mirror causes an influx of heat into the latter. This heat influx can lead to an impairment of, or damage to, the corresponding mirror.
Therefore, US 2011/0181852 A1 has disclosed the practice of connecting a corresponding mirror to a heat sink via thermally conductive elements. Here, the thermally conductive elements do not contribute, or only contribute slightly, to the bearing of the mirror. The thermally conductive elements are embodied as leaf springs. Despite their cross section only being small, an actuator for tilting the corresponding mirror works against the rigidity of the leaf springs. Accordingly, much electrical energy is supplied to the actuator. The power dissipation of the actuator arising in the process is emitted in the form of heat, which needs to be compensated for by corresponding cooling.